5 Atomic Physics. 1 of the isotope remains. 1 minute, 4. Atomic Physics. 1. Radioactivity 2. The nuclear atom

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1 5 Atomic Physics 1. Radioactivity 2. The nuclear atom 1. In a fission reactor, which particle causes a Uranium-235 nucleus to split? A. alpha-particle B. gamma ray C. neutron D. proton 2. A radioactive isotope has a half-life of 2 minutes. What can be deduced from this statement? C. have a short half-life D. make the paper radioactive 5. Two types of emission from a radioactive source are separated by passing them through a magnetic field. The deflections are shown in the diagram. A. after 2 1 minute, 4 1 of the isotope remains B. after 1 minute, 4 1 of the isotope remains C. after 4 minutes, 4 1 of the isotope remains What are the emissions P and Q? D. after 4 minutes, none of the isotope remains 3. The results of the Geiger-Marsden scattering experiment provided evidence for the presence of the nucleus with in the atom. What were scattered in this experiment? A. alpha-particles B. beta-particles C. gamma rays D. gold nuclei 6. A narrow beam of alpha-particles is fired at a thin piece of gold foil. Which is the final direction of the largest number of alpha-particles? 4. The diagram shows how thickness of paper is measured during manufacture. If the sheet is too thick, fewer beta-particles can reach the detector. A source of alpha-particles is not used for this purpose because alpha-particles A. are all stopped by the paper B. are too dangerous to those working near by 7. Ra decays with a half-life of 1600 s. Rn decays with a half-life of 52 s. Po decays with a half-life of 9.1 s Pb decays with a half-life of 10.6 s. IGCSE Physics 1 Namrata David Publications

2 The changing count rate for one of these radioactive nuclides is shown in the graph. 9. Which of the equations shows a nuclear fission reaction? From the half-life shown by the graph, which was the decaying radioactive nuclide? A. Ra C. Po B. Rn D. Pb 8. A radioactive source is placed 3 cm from a Geiger-Muller tube in air. The average count rate is 742 counts/minute. 10. Between 1909 and 1911, Geiger and Marsden carried out experiments in which alpha particles were fired at metal foil. Most of the alpha particles passes through the foil with small deflections, but some were deflected through a large angle. There results suggest that A. atoms contain clouds of electrons through which some alpha particles cannot pass B. atoms contain neutrons that alpha particles bounces off C. atoms have positive and negative charges spread throughout their volume D. atoms have positive charges concentrated in a small volume 11. A student investigates the emission from an unknown radioactive source. The source is 10 cm in front of a detector. A strong magnetic field between the source and the detector is then switched on. Then, in three experiments, measurements are taken with sheets of different materials placed between the source and the tube. The results are recorded in the table. Material of sheet Thin Aluminium Thick between source card foil lead and tube Average count rate/counts per minute Which types of radiation does the source emit? A. alpha and beta only B. alpha and gamma only C. beta and gamma only D. alpha, beta and gamma The results are shown. Which radioactive source produced these results? IGCSE Physics 2 Namrata David Publications

3 12. A detector is used to measure the count-rate near a radioactive source. The reading is 4000 counts per minute. After 30 minutes the count-rate has fallen 500 counts per minute. What is the half life of the radioactive source? You may ignore the effects of background radiation. A. 3 minutes B. 5 minutes C. 6 minutes D. 10 minutes 13. Which conclusion can be drawn from the Giger-Marsden alpha-particle scattering experiment? A. A positive charge is speared throughout the atom. B. Electrons are arranged in orbits C. Electrons are negatively charged D. There is a dense in the atom. 14. Which statement is true for all three types of radioactive emission ( alpha-particles, beta- absorbed by a thin particles, and gamma rays)? A. they are completely aluminium sheet B. they are deflected by electric fields C. they emit light D. they ionize gases 15. The diagram shows one type of radiation passing between the poles of a strong magnet and being detected. 17. Which of the following occurs in the decay of a radioactive nucleus? A. the nucleus absorbs another nucleus B. the nucleus absorbs at least one form of radiation C. the nucleus always splits into two equal fragments D. the nucleus emits at least one form of radiation 18. The table shows the possible properties of radioactive emissions. Which emission could be a beta-particle? 19. A pupil investigates the penetrating power of radiation from a radioactive source. The table shows her results. 16. Which type of radiation is being detected? A. alpha-particles only B. beta-particles only C. gamma-rays only D. alpha-particles and beta-particles A nuclide has the notation X. Which line in the table describes a different isotope of this nuclide? The source emit A. alpha and beta-particles B. beta-particles and gamma-rays C. beta-particles only D. gamma-rays only IGCSE Physics 3 Namrata David Publications

4 20. Which particle is positively charged? A. alpha-particle B. beta-particle C. electron D. neutron 21. Atoms P and Q are isotopes. How does the composition of neutral atom P compare with neutral atom Q? 22. X, Y and Z are three types of radiation. X is almost completely absorbed by 5 cm lead but not by 5 mm of aluminium. Y is almost completely absorbed by 5 mm aluminium but not by thin card Z is absorbed by thin card. What are X Y and Z. X Y Z A alpha beta gamma B beta alpha gamma C gamma alpha beta D gamma beta alpha 23. The nucleus of a nitrogen atom can be represented as 14 7 N. The nucleus of this atom consists of A. 7 protons and 7 electrons B. 7 protons and 7 neutrons C. 14 protons and 7 electrons D. 14 protons and 7 neutrons 24. Three nuclei P,Q and R have proton numbers( atomic numbers) and nucleon numbers ( mass numbers) as shown. Which nuclei are isotopes of the same element? A. P and Q only B. P and R only C. Q and R only D. P,Q and R 25. When dealing with radioactive substances there are possible dangers. Which statement is correct? A. beta-particles can pass through skin and damage body cells B. gamma-radiation is more dangerous than alpha or beta because it has longer halflife C. materials that emit only alpha-particles must be kept in thick lead containers D. radioactive materials are safe to handle after two half-lives 26. A nucleus consists of 90 protons and 144 neutrons. After emitting two beta-particles followed by an alpha-particle, this nucleus has A. 86 protons and 140 neutrons B. 86 protons and 142 neutrons C. 90 protons and 140 neutrons D. 90 protons and 142 neutrons 27. Deuterium 2 1 H and tritium 3 1 H are two isotopes of hydrogen. Compared to a deuterium atom, how many protons and neutrons does a tritium atom have? 28. A nucleus is represented by Z. It emits one alpha-particle and then one beta-particle. What is the resulting nucleus X? 226 A. X C B. X D X 89 X 29. A nuclide of the element plutonium is Pu. What is the number of neutrons in its nucleus? A. 94 C. 242 B. 148 D Which statement defines isotopes? A. two(or more) nuclides which have the same number of protons but different number of electrons IGCSE Physics 4 Namrata David Publications

5 B. two(or more) nuclides which have the same number of neutrons but different number of electrons C. two(or more) nuclides which have the same number of neutrons but different number of protons D. two(or more) nuclides which have the same number of protons but different number of neutrons 31. The diagram shows the apparatus used in an experiment in which barriers of various materials are placed in turn between different radioactive sources and a detector. The table shows the count rates recorded by the detector for four sources. Which source emits alpha-particles only? 32. A nucleus of sodium, Na has 11 protons and 12 neutrons. Which symbol represents this nucleus? 11 A. Na B Na C. 23 Na D. Na The half-life of a radioactive material is 24 years. The activity of a sample falls to a fraction of its initial value after 72 years. What is the fraction? A. 1/3 C. 1/6 B. 1/4 D. 1/8 34. Which is the correct comparison of the penetrating power and ionizing power of alpha-particles and gamma radiation? 35. The uranium nucleus U emits an alphaparticle to become thorium, which then emits a beta-particle to become protactinium. What is the proton number ( atomic number) of protactinium? A. 95 C. 90 B. 91 D The half-life of a radio isotope is 2400 years. The activity of a sample is 720 counts/s. How long will it take for the activity to fall to 90 counts/s? A. 300 years B years C years D years 37. The neutral atoms of all isotopes of the same element contains the same number of A. electrons and protons B. electrons and neutrons C. neutrons only D. neutrons and protons IGCSE Physics 5 Namrata David Publications

6 38. What is a beta-particle? A. a helium nucleus B. a high-energy electron C. four protons D. two neutrons 39. The diagram shows a radioactivity experiment. 44. A small amount of a radioactive isotope contains 72 billion unstable nuclei. The halflife of the isotope is 4 hours. How many unstable nuclei would remain after 12 hours? A. 6 billion B. 9 billion C. 18 billion D. 24 billion 45. How many nucleons are in a nucleus of K? A. 19 C. 39 B. 20 D When a piece of paper is used as the absorber, the count rate drops to the background count rate. What radiation is the source emitting? A. alpha only B. beta only C. gamma only D. alpha, beta and gamma Ne represents an atom of neon. How many neutrons does it have? A. 10 C. 22 B. 12 D Which type of radiation can be stopped by a sheet of paper? A. - particles B. -particles C. -rays D. X-rays 42. The half-life of a radioactive substance is 5 hours. A sample is tested and found to contain 0.48 g of the substance. How much of the substance was present in the sample 20 hours before the sample was tested? A g C g B g D g 46. Which type of radiation has the greatest ionizing effect? A. - particle B. - particle C. -rays D. all have the same ionizing effect 47. A powder contains 400 mg of a radioactive material that emits - particles. The half-life of the material is 5 days. What mass of that material remains after 10 days? A. 0 mg C. 100 mg B. 40 mg D. 200 mg 48. In the symbol below, A is the nucleon number and Z is the proton number. What is represented by the symbol? A. an electron B. a neutron C. a nuclide D. an X-ray 49. The diagram shows five atoms in a radioactive substance. The atoms each give out an -particle. 43. Which line correctly describes -particles? IGCSE Physics 6 Namrata David Publications

7 Atom 1 is the first to give out a particle. Atom 3 is the second to give out a particle. Which atom will give out the next particle? A. atom 2 B. atom 4 C. atom 5 D. impossible to tell 50. A Geiger counter detects radiation from radioactive sources. A radioactive source is inside a thick aluminium container as shown. How much of the substance was present in the sample 20 hours before the sample was tested? A g C g B g D g 54. The data below relates to the nucleus of a particular neutral atom of nitrogen. Proton number Z = 7 Neutron number A = 17 Which row represents the correct number of neutrons and electrons in this atom? Which type of radiation from this source is being detected? A. - particles B. - particles C. -rays D. radio waves 51. The nucleus of a neutral atom of lithium is represented by 7 3 Li. How many protons, electrons and neutrons does the atom contain? 52. What are the most penetrating and the least penetrating types of radiation? 53. The half-life of a radioactive substance is 5 hours. A sample is tested and found to contain 0.48 g of the substance. 55. A radioactive source emits radiation that can pass through a sheet of paper but not through thick aluminium. What does this show about the radiation? A. it is alpha-particle B. it is beta-particles C. it is gamma-rays D. it is a mixture of alpha-particles and gamma rays 56. A sample of a radioactive isotope is decaying. Which atoms will decay first? A. impossible to know, because radioactive decay is random B. impossible to know, unless the age of the material is known C. atoms near the centre, because they are surrounded by more atoms D. atoms near the surface, because the radiation can escape more easily 57. Which line in the table describes the nature of an alpha-particle and gamma-ray? IGCSE Physics 7 Namrata David Publications

8 of the storeroom. The radiation was emitted by the radioactive material. 58. A radioactive nucleus R decays with the emission of a beta particle as shown. Which equation is correct? A. x = p B. y = q C. p = x 1 D. q = y Which line in the table shows the structure of the nucleus of a helium atom 4 2 He? Which type of radiation was being detected? A. - particles B. - particles C. -rays D. X-rays 63. How many neutrons are in a nucleus of 14 6 C? A. 0 C. 8 B. 6 D A radioactive source emits radiations that can pass through a sheet of paper but not through thick aluminium. 60. A nucleus of substance X has the symbol X. How many electrons orbit around the nucleus of a neutral atom of substance X? A. 12 C. 26 B. 14 D The equation shows the decay of the nuclide X. What are the values of P and Q? What does this show about the radiation? A. it is alpha-particles B. it is beta-particles C. it is gamma-rays D. it is a mixture of alpha and gamma particles 65. An unstable nucleus has 145 neutrons and 92 protons. It emits a beta-particle. How many neutrons and protons does the nucleus have after emitting the beta-particle? 62. During a fire in a laboratory store room, some radioactive material was spilled. A firefighter detected radiation through the lead-lined walls IGCSE Physics 8 Namrata David Publications

9 66. Which particles are found in the nucleus of an atom? A. neutrons only B. neutrons and protons only C. protons and electrons only D. protons, electrons and neutrons 67. Which line in the table describes the nature of an alpha-particle and of gamma-ray? 68. The count rates of four radioactive sources were measured at the same time on three consecutive days. Which source has a half-life of two days? Which types of radiation can pass through the paper? A alpha and beta particles only B. alpha particles and gamma rays only C. beta particles and gamma rays only D. alpha and beta particles and gamma rays 72. An atom of the element lithium has a nucleon number of 7 and a proton number of 3. Which diagram represents a neutral atom of lithium? 69. Which statement is true of all neutral atoms? A. the number of electrons equals the number of nucleons. B. The number of neutrons equals the number of protons C. The number of nucleons equals the number of neutrons D. The number of protons equals the number of electrons 70. There are three nuclides of hydrogen. Which of these nuclides have the same number of protons in their nuclei? A. 1 and 2 only B. 2 and 3 only C. All of them D. None of them 71. A sheet of paper is placed between a radioactive source and a detector. IGCSE Physics 9 Namrata David Publications